Metal-to-metal seals are widely used for sealing against fluid pressure in the spacing between the facing surfaces of one member disposed within the tubular bore of another. Such prior art metal-to-metal seals, and particularly those of annular configuration which are U-shaped in radial cross section, generally have relatively low tolerance with respect to rough finishes on surfaces with which they are to seal and generally require pre-loading. They are also characterized by a high modulus of elasticity and thus require relatively large actuating loads since the actuating load is required to exceed the yield strength of the seal material so that it will become sufficiently plastic to flow into the irregularities of the roughened surface with which it is to seal. Furthermore, the prior art seals are typically unidirectional and require relatively long actuating strokes since they are characteristically provided with relatively long "U" legs (seal lips) as a means of increasing their flexibility but which also make it difficult to achieve the necessary plasticity for an effective seal.